A known paper sheet bundling apparatus bundles various paper sheets typified by banknotes using a bundling band for each predetermined number of sheets, and affixes a stamp to the bundling band after the bundling (see, for example, Patent Literature 1). Moreover, another known paper sheet bundling apparatus checks the printing density of a stamp affixed to a bundling band, and adjusts stamp affixing time and stamp affixing intervals on the basis of the checking results, to thereby stabilize a stamp affixing state (see, for example, Patent Literature 2).
If a plurality of paper sheets are put on top of each other, irregularities occur on the surface due to ink, security threads, and the like. There is a problem that, if portions in which such irregularities occur are bundled using a bundling band and a stamp is affixed thereto, partial missing of the affixed stamp occurs, and the affixed stamp is difficult to read.